Each slice combines caramelization and flavor: the appetizer dish that leaves its mark

This savory tart with caramelized onions is a refined and visually stunning rustic pizza, perfect as an appetizer or a buffet snack. You can also serve it as a main course, adding a protein boost (like cheese) or pairing it with a generous portion of mixed salad.

What to know before you start

Inspired by the famous French tarte tatin, this savory tart with caramelized onions is also "upside down." It's made upside down, with the onions on the bottom and the shortcrust pastry on top. The preparation is simple, but the flavor is nothing short of superb.

We made our own puff pastry, but you can also buy ready-made bases. If you want to follow our example (it's incredibly easy to make and can't be compared to commercial products), you just need to be careful: use very cold butter and almost ice-cold water, to prevent the gluten from overdeveloping.

As for the onions, however, you need to try to keep the concentric rings compact both when cutting and during the initial sautéing in the pan. It doesn't affect the flavor, mind you, just the appearance of the tart once you invert it onto the serving plate.

One last tip concerns the choice of cake pan. To prevent the glaze from leaking, use a springform pan lined with parchment paper or a traditional nonstick pan.

Substitute and additional ingredients

If you don't want to use butter for the shortcrust pastry, replace it with 80 ml of extra virgin olive oil (reducing the water to 40 ml). As an alternative to balsamic vinegar, especially if you want a more delicate flavor, use apple cider vinegar. To enrich the filling and transform the recipe into a full-course meal, you can add cubes of goat cheese, crumbled feta, or gorgonzola.

Instead, for an extra crunch, place chopped walnuts between the onion layer and the shortcrust pastry before baking.

For the filling

• Salt 1 pinch

Preparation

• In a bowl, combine the flour, salt, and cold butter. Quickly work the mixture with your fingertips until it resembles sand. Pour in the ice water and quickly knead until it forms a smooth dough. Wrap in plastic wrap and refrigerate for 30 minutes.
• Slice the onions, aiming for a thickness of about 1 cm, keeping the concentric rings intact. Place them in a large pan with the balsamic vinegar, brown sugar, and a pinch of salt. Cook over high heat for a couple of minutes, without stirring, but moving the pan in a circular motion until the sugar dissolves and a glaze forms. Gently flip the onions with a spatula and cook on the other side for another 2 minutes.
• Arrange the onions on the bottom of a baking pan previously lined with parchment paper, trying to leave no empty spaces. Transfer the remaining glaze to a small bowl. Roll out the shortcrust pastry on a floured surface and then place it on top of the cooled onions, tucking the edges in slightly. Prick the surface with a fork and bake in a preheated oven at 200°-220°C for about 20 minutes, until golden brown.
• Remove from the oven and invert the still-warm tart onto a serving plate or wire rack. Cover the surface with the reserved glaze, let it cool, and then serve.

Don't overcook the onions in the pan to avoid them releasing too much liquid and falling apart during baking. If using a springform pan, wrap the outside of the base in aluminum foil to prevent caramel dripping in the oven. Remember to invert the tart immediately after baking, because if it cools in the pan, the glaze may solidify, making it difficult to remove from the pan. If you want an even crispier crust, bake on the lowest rack of the oven for the first 10 minutes, then finish baking on the middle-upper rack.

The savory tart with caramelized onions can be stored in the refrigerator, in an airtight container, for up to 2-3 days. Before serving, reheat it in a preheated oven at 180°C (350°F) for 8-10 minutes to restore the crispness of the shortcrust pastry. This recipe is not suitable for freezing.

Serve the tart warm or at room temperature. Cut it into even slices, keeping the onion rings in the center of each portion. Garnish with a sprig of fresh thyme and a few drops of balsamic vinegar on the plate.

A structured white wine with good acidity like Vermentino di Sardegna is perfect, but a Franciacorta brut also works well. If you prefer beer, opt for a craft beer like Belgian Pale Ale or Bock.